1. Field
Device to device (D2D) communication can employ various acknowledgment schemes. In particular, D2D communications can assist the use of acknowledgment, by a cluster, of a multicast message sent to the cluster.
2. Description of the Related Art
Multicast services are becoming more and more popular with the development of cellular wireless networks (e.g. long term evolution (L 1E) networks), where data is transmitted to multiple recipients by an evolved Node B (eNodeB) or similar base station device. By utilizing the shared nature of wireless medium, multicast service can be realized with a high efficiency. In order to support reliable packet delivery in multicast service, hybrid automatic repeat request (HARQ) protocol can be incorporated into the packet multicasting process, i.e. each device in the recipient cluster will feedback an acknowledgement and negative acknowledgement (ACK/NACK) message for each of the multicast packets; and a packet will be retransmitted if a NACK message is reported by the service recipient. Typically, the HARQ acknowledgement is packet-wise, i.e., every packet recipient reports its own acknowledgment to the control node in universal terrestrial radio access network (UTRAN) and enhanced UTRAN (E-UTRAN), the control node retransmits the packet according to the received HARQ acknowledgement.
For multicasting service with a device-to-device (D2D) cluster, the HARQ acknowledgement for requesting the retransmission or new transmission from eNodeB is one of the signaling elements to be considered. Because a cluster of devices may need to feed back the HARQ acknowledgement, optimization of HARQ feedback signaling for a cluster of devices can help to control the efficiency of uplink control signaling and minimize its impact on system efficiency.